It is well known to deposit coatings of material on a conductive core by electrophoretic deposition (EPD). EPD is a combination of electrophoresis and deposition. Electrophoresis is the movement of charged particles in an electric field. Deposition is the coagulation of particles into a mass. Applicant's own PCT application no. PCT/CA01/00634 relates generally to the production of hollow ceramic membranes by EPD, and in particular to the production of hollow ceramic electrodes by EPD for solid oxide fuel cells (SOFC).
In general, a SOFC comprises two electrodes (anode and cathode) separated by a ceramic, solid-phase electrolyte. To achieve adequate ionic conductivity in such a ceramic electrolyte, the SOFC operates at an elevated temperature, typically in the order of about 1000° C. The material in typical SOFC electrolytes is a fully dense (i.e. non-porous) yttria-stabilized zirconia (YSZ) which is an excellent conductor of negatively charged oxygen (oxide) ions at high temperatures. Typical SOFC anodes are made from a porous nickel/zirconia cermet while typical cathodes are made from magnesium doped lanthanum manganate (LaMnO3), or a strontium doped lanthanum manganate (also known as lanthanum strontium manganate (LSM)). In operation, hydrogen or carbon monoxide (CO) in a fuel stream passing over the anode reacts with oxide ions conducted through the electrolyte to produce water and/or CO2 and electrons. The electrons pass from the anode to outside the fuel cell via an external circuit, through a load on the circuit, and back to the cathode where oxygen from an air stream receives the electrons and is converted into oxide ions which are injected into the electrolyte. The SOFC reactions that occur include:
Anode reaction:                H2+O=→H2O+2e−        CO+O=→CO2+2e−        CH4+4O=→2H2O+CO2 +8e−        
Cathode reaction:                O2+4e−→2O=        
Known SOFC designs include planar and tubular fuel cells. Applicant's own PCT application no. PCT/CA01/00634 discloses a method of producing a tubular electrode supported electrochemical fuel cell by                (a) electrophoretically depositing an anodic or cathodic material onto a fibre core to create a porous electrode layer;        (b) depositing a solid electrolyte layer onto the electrode layer;        (c) drying and sintering the core bearing the deposited material or cathode layer and the solid electrolyte layer at a temperature and for a length of time sufficient to combust the fibre core and to create a fully dense electrolyte layer while maintaining the porosity of the inner electrode layer;        (d) depositing an outer electrode layer onto the solid electrolyte layer, which is of an anodic material if the inner layer comprises a cathodic material, or a cathodic material if the inner layer comprises a anodic material;        (e) sintering the end product at a temperature and for a length of time sufficient to bond the outer layer to the solid electrolyte layer while maintaining the porosity of the outer and inner electrode layers.        
In the completed fuel cell, the inner electrode may be the anode, and the outer electrode may be the cathode. In such case, fuel may be supplied to the anode by passing through the tube, and air may be supplied to the cathode by passing over the outer surface of the tube.
While this PCT application discloses producing tubular ceramic fuel cells by EPD, it may be desirable to produce hollow inorganic membranes having characteristics that are different than the hollow ceramic membranes produced by EPD as described in this PCT application. For example, it may be desirable to produce a hollow inorganic membrane having a different shape, composition, ductility, fracture toughness, and/or microstructure than a ceramic membrane produced by EPD, wherein such characteristics are particularly suitable for certain fuel cell applications.